道管要素の叩解挙動とシートのピッキング

広葉樹パルプの基礎的研究 第4報

抄録

The sample pulps were prepared by blending with Bagtikan (Parashorea plicata) or Narig (Vatica mangachapoi) vessel element (henceforth referred to as vessel) pulp and Makanba (Betula maximowicziana) or Mangrove (Rhizophora sp., Bruguiera sp.) wood fiber (henceforth referred to as fiber) pulp, which had been separated by the method using a flat screen equipped with screen wire from the corresponding kraft pulp. The breaking tendency of vessels during beating process was assessed by examining the number ratio of whole, broken and fragmented vessels in the suspensions. The pick number and the surface strength of the handsheets from unbeaten and beaten blended pulps were measured by using the IGT printability tester and the wax pick test.
The broken or fragmented vessels increase with increasing beating degree. This tendency is noticeable for the pulps blended with Mangrove fibers and/or Bagtikan vessels. For this reason, the cell wall thickness of fibers and the size and/or distribution of pits in vessels were suggested. When blended with Mangrove fibers, the wax number is small and the pick number is large, in spite of pronounced breaking of vessels. This indicates that the bonding strength between fibers and vessels may be a major factor, and that the breaking of vessels may be a minor one in picking. A comparison between the vessel projected area size distribution and the pick area size distribution for the pulps showed that smaller vessels were apt to be picked than bigger vessels.